The effects of dipping in water for a long period ontensile properties of spheroidal graphite cast iron (SG iron) havingvarious matrices was investigated from the viewpoints ofcorrosion and water embrittlement. The tensile strength andelongation of ADI, pearlitic and quench-tempering SG iron, testedunder the wet condition after immersing in water for 480 hours,were lower than those in air and in condition of contact with water,drastic water embrittlement was observed. Especially, ADI showedthe most remarkable water embrittlement. When the specimenswere dipped in tap water for a long period, the water embrittlementwas increased more remarkably than the specimens dipped in ionexchange water. This is because the growth of corrosion pits waspromoted by the tap water. In the case specimens were dipped inthe tap water for a long period, the tensile strength and elongationwere recovered to a certain degree by drying. The tensile propertiesof specimen dried after immersing were not completely recoveredto the level tested in air because of reduction of cross sectionalarea due to the corrosion pits and surface dissolution. The tensileproperties of ferritic SG iron dipped in the tap water for a longperiod had little effect, only the small reduction of tensile strengthand elongation was observed.
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